U.S. officials to require mandatory studies of how proposed wind energy projects will affect birds, including those under consideration for endangered status. According to the group, at least 440,000 birds are killed each year by collisions with wind turbines — including thousands of golden eagles at the Altamont Pass wind farm in California — and the number will likely increase to 1 million annually by 2020 as the industry continues to grow. “We’ve had voluntary guidelines since 2003, and yet preventable bird deaths at wind farms keep occurring,” the group said. Regulatory language proposed by ABC would also give the wind industry legal assurance that permitted projects would not be subject to criminal or civil penalties for violation of the Migratory Bird Treaty Act. The group is also urging an emphasis on “bird smart” siting and operation of wind farms, including burying transmission lines and building turbines in areas that have already been altered or developed, such as farmland.